Rich Dad, Poor Dad was written by a salesman but the point was pretty good. I read it when I was fairly young and it taught me to buy things that make money not cost money.
Personally I felt it was a pretty good resource but you could tell he was trying to sell his additional books in it. That IMO took away from some of the authenticity of it.
Still a good read for those who don't have wealthy parents to teach them these things. I grew up in a household that spent what it made on new cars, vacations, clothes, eating out, etc.